# At STP a 7.49-gram sample of an element has a volume of 1.65 cubic centimeters. What is the element?

Dec 14, 2016

The element is titanium, $\text{Ti}$.

#### Explanation:

The density (ρ) of anything is its mass ($m$) divided by its volume ($V$).

color(blue)(bar(ul(|color(white)(a/a)ρ = m/Vcolor(white)(a/a)|)))" "

In this problem,

$m = \text{7.49 g}$
$V = {\text{1.65 cm}}^{3}$

ρ = m/V = "7.49 g"/("1.65 cm"^3) = "4.54 g/cm"^3

We consult a list of chemical elements sorted by density.

ρ"/g·cm"^"-3"color(white)(m)"Element"color(white)(m)"Symbol"color(white)(m)"At. No."
stackrel(—————————————————)(color(white)(m)4.47color(white)(mm)"Yttrium"color(white)(mmll)"Y"color(white)(mmmm)39)
$\textcolor{w h i t e}{m} 4.54 \textcolor{w h i t e}{m m} \text{Titanium"color(white)(mm)"Ti} \textcolor{w h i t e}{m m m l l} 22$
$\textcolor{w h i t e}{m} 4.79 \textcolor{w h i t e}{m m} \text{Selenium"color(white)(mml)"Se} \textcolor{w h i t e}{m m m l l} 34$

The three most likely elements are $\text{Y, Ti}$, and $\text{Se}$.

The element is probably titanium, $\text{Ti}$.